1. Field of the Invention
The present invention relates to an image forming apparatus using an electrophotography method or an electrostatic recording method, and, more particularly, to an image forming apparatus, such as a copying machine, a printer, or a facsimile.
2. Description of the Related Art
Nowadays, a demand for reducing running cost in terms of image output of an electrophotography image forming apparatus is increasing more and more. To meet this demand, the amount of toner consumption may be reduced.
For example, hitherto, a toner saving mode in which the amount of toner consumption is less than the amount of toner consumption in an ordinary mode is provided (refer to Japanese Patent Laid-Open No. 6-14167). More specifically, when the toner saving mode is selected, a development bias is changed from a development bias in the ordinary mode, to perform a controlling operation that reduces the amount of toner used for development.
However, when, as in the apparatus discussed in Japanese Patent Laid-Open No. 6-14167, the amount of toner consumption is reduced, the density of an output image may be reduced with respect to an original image.
In an image forming apparatus using both dark toner and light toner having different brightnesses and the same hue, when the amount of toner consumption is to be reduced, the dark toner may be selectively used to form an image, whereas, when image quality is given priority, the dark toner and the light toner may both be used to form an image.
However, in such a structure, an image forming section for the dark toner and an image forming section for the light toner need to be provided. Therefore, the apparatus is increased in size and becomes sophisticated.